In the field of aeronautics, aircraft flight displays present a piloting symbology which is increasingly often enriched with other synthetic images such as cartographic images (MAP) or with synthetic vision images (SVS) situated either under this symbology or in adjacent surfaces, the surface available on current displays allowing this function. More generally the images of flight displays may also be composed of multiple windows that can have different refresh rates, variable positionings and sizes and that need if necessary to be mixed together in accordance with a particular order, which may change however. These images also comprise elements created by software tasks having different criticality levels.
There exist screen controllers that may or may not be integrated with graphical generation functions which ensure a form of hardware support for the functionalities offered by software of operating systems, however although the latter ensure the display of surfaces created off-screen, none exist that do so while ensuring automatic sorting and variable mixing, nor which are able to control cursor generators and video mixers. Quite often moreover the support for windowing is ensured by software in a mode which is akin to a selection of all or nothing type between surfaces, only recent operating systems for the mass market include functions for mixing between superimposed surfaces but this is purely for aesthetic purposes or at best as a memory aid since the content of the lower surfaces is most often made unreadable by the introduction of blurring.
There exist automatons allowing image composition at the pixel level but management of priority is performed globally at the window level. Mixing with management of transparency sometimes has hardware support but is most often done in a non real-time software manner. The number of constituent surfaces of an image is limited by the size of the associated hardware.
The objective of the invention is to propose a method for generating images making it possible to improve the management of the images with multiple windows having a variable display priority, the aim being to increase the flexibility of management of the windows and to reduce the bandwidth required for the video stream.